Size and Aggregation of Corticosteroids Used for Epidural Injections

Abstract

Compared with the particulate steroid solutions, dexamethasone sodium phosphate had particles that were significantly smaller than red blood cells, had the least tendency to aggregation, and had the lowest density. These characteristics should significantly reduce the risk of embolic infarcts or prevent them from occurring after intra-arterial injection. Until shown otherwise in clinical studies, interventionalists might consider using dexamethasone or another corticosteroid preparation with similar high solubility and negligible particle size when performing epidural injections.

Particulate versus non-particulate steroids for lumbar transforaminal or interlaminar epidural steroid injections: an update

“…It was hypothesized that spinal cord infarction due to embolization of particulate steroids, needle-induced vasospasm, compression from an epidural hematoma or abscess and mechanical disruption of radiculomedullary arteries are possible mechanisms of spinal cord injury in patients undergoing cervical and lumbar epidural infiltrations [13][14][15]31]. Noteworthy, benzyl alcohol, which is added as a preservative in many commercially available preparations, has been reported to be neurotoxic.…”

“…Subsequently, infarction of the brainstem, cerebellum, and the spinal cord may occur. One might speculate that steroid particles smaller than the diameter of an erythrocyte are safer [31].…”

“…In contrast, dexamethasone sodium phosphate is considered as freely water-soluble. Thus, dexamethasone preparations are allocated to the non-particulate steroid group, despite the fact that some sporadic and small particles might be seen under the microscope with a typical particle size of 0.5 μm [31,49,50]. Betamethasone preparations are outliers of this binary classification: betamethasone preparations are commonly a mixture of betamethasone acetate (insoluble needing esterase activation) and betamethasone sodium phosphate (in solution) and provide characteristics of both groups, the particulate and nonparticulate steroids [31,49,50].…”

“…Thus, dexamethasone preparations are allocated to the non-particulate steroid group, despite the fact that some sporadic and small particles might be seen under the microscope with a typical particle size of 0.5 μm [31,49,50]. Betamethasone preparations are outliers of this binary classification: betamethasone preparations are commonly a mixture of betamethasone acetate (insoluble needing esterase activation) and betamethasone sodium phosphate (in solution) and provide characteristics of both groups, the particulate and nonparticulate steroids [31,49,50]. Moreover, there are also substantial differences in the propensity of different corticosteroid particles to aggregate into larger particles depending on the chemical ingredient (esters with larger particulate size), on the varying concentrations, on the drug vehicle, or on the drug mixtures with local anesthetics and/or contrast media prepared in-situ for pain treatment [50].…”

“…The image noise is related to a low-dose protocol (120 kVp, 8 mAs) and the obesity of the patient magnification (×400 and ×1000) [31]. Derby et al [31] have shown that the largest triamcinolone acetonide particles (range, 0.5-100 μm) were more than 12 times greater than median-sized erythrocytes (approximately 7.5 μm) [31]. Triamcinolone and betamethasone particles were densely packed with an extensive particle aggregation, e.g., some betamethasone aggregations were larger than 100 μm.…”